From Berhard Sklar, "Digital Communications" Prentice Hall, Englewood Cliffs, N.J., 1988, page 290 et seq., an encryption method is known in which encoding is performed by means of a shift register. This method has the disadvantage that the encoding technique can be easily discovered, so that the encoded data can be easily decrypted.
Furthermore, the so-called RC-4 algorithm is known, in which quasi-random encryption words are generated by performing different arithmetic operations. This algorithm has the disadvantage that a great amount of storage space is necessary for good encryption.
The object of the invention is to provide a method for encrypting or decrypting a data sequence which is difficult to decrypt, does not require much storage space, and can be implemented on silicon at low cost.